'MSCONTACTS' cannot be opened

[HeyRobi]

I was trying to use Icontacts as my default contacts but i could not get it to work now when I click on Phone on the home page then Contacts I get an error that says 'MSCONTACTS' cannot be opened..... Does anyone know what registry key I need to edit to get it to work again. I forgot which one I edited! FYI if I click on the phone tab and "all contacts" my contact list comes up.